The main factor that may weaken the stability of the roof structure is dampness. On its negative impact it is particularly exposed rafter framing, which deform under impact of water. Therefore is important roof protection against getting in  water into its internal structure.

Typically, investors during the construction of the roof attach great importance both for building materials, as well as careful execution. Unfortunately, later very often they forget about the survey, and any minor defects  commission outsource cheaper and often non-professional roofing companies. This is a big mistake,

Metal roof "oil canning" any experts? Festool Owners Group There are some different systems out there, but conventional metal roofing wisdom says that you have to install the lower roofing first, then the Z mould, transition. ACS Roofing Roofing for the Future Welcome to ACS Roofing.

A very important element that must be considered when the roof is projected, is ventilation, allowing drainage of excess dampness from under the roofing.